title: Possible objectification of a critical maximum diameter for elective surgery in abdominal aortic aneurysms based on one- and three-dimensional ratios.
abstract: BACKGROUND
  The purpose of this study was to evaluate the ratio of aneurysm size to aortic diameter (dm/ds) and newly defined volumetric parameters and to objectify by means of these parameters a critical maximum diameter (dm) as indicator for elective surgery of abdominal aortic aneurysms (AAA).
  
  
  METHODS
  Based on contrast-enhanced CT scans one- and three-dimensional parameters were measured in 3 groups of n=58 patients selected for a) emergency surgery (n=13) in case of contained rupture and b) elective surgery (n=29) or c) non operative follow-up (n=16) if the AAA was bigger or smaller than 4.5 cm in dm. Ignoring these groups the statistically independent ratios dm/ds and thrombus to aneurysm volume (TV/AV) of all patients were retrospectively subjected to cluster and regression analyses in order to find out possible critical values confirming a dm-based decision. Thrombus (TV) and aneurysm volume (AV) correlated with increasing diameter.
  
  
  RESULTS
  The ratio TV/AV predominantly increased from 0.42 to 0.65 in aneurysms 5 to 8 cm in diameter, reaching a maximum of 0.8 in AAA with contained rupture. A TV/AV of 0.45 and a dm/ds of 2.0 were found to be separators of two distinguished groups confirming a critical dm of about 5 cm.
  
  
  CONCLUSIONS
  The newly defined volumetric ratio TV/AV and dm/ds may objectify the dm-based decision for elective surgery or follow-up treatment. Prospective studies have to evaluate this approach.
authors.affiliation: Department of Surgery, Klinikum Grosshadern, Ludwig-Maximilians University, Munich, Germany.
authors.forename: W A
authors.initials: WA
authors.lastname: Cappeller
authors.forename: H
authors.initials: H
authors.lastname: Engelmann
authors.forename: S
authors.initials: S
authors.lastname: Blechschmidt
authors.forename: M
authors.initials: M
authors.lastname: Wild
authors.forename: L
authors.initials: L
authors.lastname: Lauterjung
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001012:Aorta, Abdominal / Q000473:pathology*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D016000:Cluster Analysis; D003657:Decision Making; D016002:Discriminant Analysis; D017558:Elective Surgical Procedures; D006801:Humans; D008875:Middle Aged; D011856:Radiographic Image Enhancement; D014057:Tomography, X-Ray Computed